Transporting fibre channel over ethernet

ABSTRACT

Methods and apparatus for the Transporting of Fibre Channel data over Ethernet are disclosed. In one embodiment of the invention, a server ( 32 ) contains a virtual Fibre Channel Host Bus Adapter (HBA) ( 40 ). The virtual Fibre Channel HBA ( 40 ) contains a number of virtual Fibre Channel N-Ports ( 42 ) and an Ethernet interface ( 44 ). The virtual Fibre Channel HBA ( 40 ) is connected to an Ethernet layer ( 2 ) switch ( 24 ) via an ethernet local area network ( 21 ). The Ethernet layer ( 2 ) switch ( 24 ) is also connected to an FCoE Transformer ( 46 ) via an ethernet local area network ( 21 ). The FCoE Transformer ( 46 ) is connected to the Fibre Channel storage area network ( 20 ). Contained within the FCoE Transformer ( 46 ) are a number of real Fibre Channel N-Ports ( 48 ) that correspond to the virtual Fibre Channel N-Ports ( 42 ).

CROSS-REFERENCE TO RELATED PENDING PATENT APPLICATIONS & CLAIMS FORPRIORITY

This application is a continuation in part of and claims priority toU.S. application Ser. No. 13/999,756, filed 18 Mar. 2014, the disclosureof which is incorporated by reference herein in its entirety.

U.S. application Ser. No. 13/999,756 in turn, is a continuation in partof and claims priority to U.S. application Ser. No. 13/385,390 filed 15Feb. 2012, the disclosure of which is incorporated by reference hereinin its entirety.

U.S. application Ser. No. 13/385,390 in turn, is a continuation in partof and claims priority to U.S. application Ser. No. 12/590,929, filed 17Feb. 2009, the disclosure of which is incorporated by reference hereinin its entirety.

U.S. application Ser. No. 12/590,929 in turn, is a continuation in partof and claims priority to U.S. application Ser. No. 11/890,288, filed 3Aug. 2007, the disclosure of which is incorporated by reference hereinin its entirety.

U.S. application Ser. No. 11/890,288 in turn, is a continuation in partof and claims priority to U.S. application Ser. No. 10/689,540, filed 21Oct. 2003, the disclosure of which is incorporated by reference hereinin its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

The present invention pertains to methods and apparatus for transportingFibre Channel data frames and primitive signals over Ethernet. MostStorage Area Networks (SANs) have been built using a technology calledFibre Channel. Most Local Area Networks (LANs) have been built using atechnology called Ethernet. When both a LAN and a SAN are required, twoseparate networks of differing technologies are used. In one preferredembodiment of this invention, enables the transport of Fibre Channeldata frames and primitive signals. In another preferred embodiment, theinvention enables the replacement of the Fibre Channel FC-1 protocol bythe Fibre Channel over Ethernet (FCoE) protocol.

BACKGROUND OF THE INVENTION

The current state of the art in computer data center networkingtechnology is based upon two different types of networks; Local AreaNetworks (LANs) and Storage Area Networks (SANs).

The LAN is a general-purpose network for server-to-server andserver-to-Internet communication, typically carrying TCP/IP traffic overhigh-speed Ethernet (Fast Ethernet or Gigabit Ethernet). Ethernet, inits various forms, is the dominant LAN technology in use today. TheEthernet standards are governed by the IEEE (Institute Electrical andElectronics Engineers) LMSC (LAN/MAN Standards Committee) 802. Thevarious standards that comprise Ethernet have evolved over time todescribe a robust and flexible set of Physical (layer 1) and MAC (layer2) protocols. Collectively taken together as Ethernet, this LANnetworking technology has demonstrated exceptional interoperabilitybetween multiple equipment vendors and great adoption by the computingindustry resulting in market adoption approaching 90%. This marketdominance has enabled Ethernet component vendors to produce products ona very large scale and to reduce costs and pricing over time. Inaddition to being the dominant LAN networking technology, Ethernet isalso the most cost effective LAN technology.

The SAN is a special-purpose network for server-to-storagecommunication, typically implemented using Fibre Channel technologybecause of its high-performance characteristics. Fibre Channel, in itsvarious forms, is the dominant SAN technology in use today. The FibreChannel standards are governed by the INCITS (InterNational Committeefor Information Technology Standards) Technical Committee 11. Thevarious standards that comprise Fibre Channel have evolved over time todescribe a set of layer 1 through layer 4 protocols. Collectively takentogether as Fibre Channel, this SAN networking technology has beenadopted by disk drive manufacturers as the primary SAN interface fortheir products. Despite the standardization efforts, Fibre Channel hasbeen plagued with interoperability issues. Although Fibre Channel is thedominant SAN technology, the interoperability issues and a smallermarket for SANs has kept costs and prices for Fibre Channel equipmenthigh, much higher than comparable speed Ethernet equipment.

Servers, which are connected to both networks, use the SAN to accessremote storage and the LAN for all other communication. This two networkarchitecture offers considerable benefits, derived chiefly from thedissociation of storage from the physical server. If applications storestate information in remote storage, then a spare server can replace afailed server simply by connecting to the SAN. Similarly, applicationscan access spare processing capacity if idle servers are added, and theremote storage is used to coordinate the work of the new servers. Thisimproved availability and manageability makes scaling out the datacenter possible, and scalability is necessary to support growing clientdemands. Although the LAN/SAN architecture provides increasedflexibility and functionality, this approach also has drawbacks. Thefact that it consists of two networks—and is thus a disjointedcommunication infrastructure—implies considerable support overhead.Because the LAN and SAN differ in their basic technologies and usage,most data centers have necessarily evolved two separate technicalcultures for their respective support. This schism also manifests in thesoftware abstractions required to manage the data center. Separateadministrative consoles exist for server and application functions andfor storage services. Although the LAN/SAN segregation does not causethis fragmentation of management interfaces, it does not mitigate thefragmentation either. Finally, maturity of SAN standards significantlylags behind that of the more general-purpose LAN, diminishing return oninvestment (ROI). The LAN/SAN design is state of the art and a vastimprovement over previous architectures, but it is an intermediate stepin data center evolution.

A unified LAN/SAN is the next step—it will enable SAN devices to beaccessed using LAN technology. The emergence of new interconnecttechnologies will provide a single, standards-based infrastructure forboth general-purpose and high performance networking requirements.Recent attempts at providing SAN connectivity over LAN have primarilyinvolved running various storage protocols over TCP/IP. These protocolsare commonly known as IP storage. The three most notable efforts havebeen iSCSI, FCiP and iFCP. These protocols provide block access,tunneling and device access respectively. At the SAN device endpoint, agateway is necessary to provide a TCP connection and perform thephysical connectivity to the SAN device's native electrical interface.Because of these issues, building IP storage gateways are inherentlyexpensive.

All of the above IP storage solutions incorporate mechanisms thatrequire a TCP offload engine and associated support logic and bufferingand are expensive to implement.

The technology called Fibre Channel is governed by the TechnicalCommittee T11, within the InterNational Committee for InformationTechnology Standards (INCITS). The T11 Committee was previously known asX3T9.3 Committee. The T11 Committee has produced a number ofspecifications defining the various aspects of the Fibre Channeltechnology. One of these specifications is the, dated Jun. 1, 1994.Fibre Channel Physical and Signaling Interface (FC-PH) Rev 4.3Specification.

The Fibre Channel Physical and Signaling Interface Specification (FC-PH)Rev 4.3 dated Jun. 1, 1994 states:

-   -   “3.1.132. Primitive Sequence: An ordered set transmitted        repeatedly and continuously until a specified response is        received (see 16.4 and 24.8.1).    -   3.1.133. Primitive Signal: An ordered set designated to have a        special meaning such as an Idle or Receiver_Ready (R_RDY) (see        16.3).” FC-PH, Page 9, Col 1, Lines 41-48.

The Fibre Channel Physical and Signaling Interface Specification (FC-PH)Rev 4.3 dated Jun. 1, 1994 further states:

-   -   “3.1.154. Sequence: A set of one or more Data frames with a        common Sequence_ID (SEQ_ID), transmitted unidirectionally from        one N_Port to another N_Port with a corresponding response, if        applicable, transmitted in response to each Data frame (see        clause 24).” FC-PH, Page 10, Col 2, Lines 4-9.

The present invention, unlike the invention presented in U.S. Pat. No.6,400,730 by Latif et al. (Latif), does not require the use of IPpackets to encapsulate the Fibre Channel data. The present inventiontransports Fibre Channel data frames, Fibre Channel primitive signalsand Fibre Channel primitive sequences at over Ethernet at the MAC layerwithout using higher layer networking protocols such as IP and UDP.

The present invention, unlike the invention presented in Latif, enablesthe use of multiple Fibre Channel interfaces and multiple Ethernetinterfaces to be associated and supported by a single FCoE Transformer.Multiple Fibre Channel interfaces are enabled by the use of theInterface Port Identifierfield in the FCoE Header. Multiple Ethernetinterfaces are enabled by the use of the Interface Identifier field inthe FCoE Header. The encapsulation of Fibre Channel frame data directlywithin an Ethernet frame as described in Latif enables only a singleEthernet port and a single Fibre Channel port, greatly limiting itsapplicability and use.

The present invention, unlike the invention presented in U.S. Pat. No.7,307,995 by Iyer et al. (Iyer) does not require intermediate networkdevices, such as Ethernet switches, to be aware of individual FibreChannel data stream specific information. In an FCoE environment, allFCoE traffic is processed as Ethernet traffic. Within an FCoETransformer, the information used to select a specific Ethernet port anda specific Fibre Channel port is contained within the FCoE Header andthe FCoE Type Header. Compared with Iyer, which requires that FibreChannel data stream specific information, specifically the Exchange_ID,which is located within the FCP header, to be interrogated by the systemin order to operate. The present invention does not require thesecomplex steps to accomplish its goal.

A system that can easily, efficiently and reliably carry Fibre Channeldata frames and primitive signals over Ethernet at the MAC layer (layer2) would constitute a major technological advance, and would satisfylong felt needs and aspirations in the LAN, SAN and server industries.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for transportingFibre Channel data over Ethernet. Fibre Channel data comprises FibreChannel data frames, primitive signals and primitive sequences.Transporting Fibre Channel data over Ethernet enables existing Ethernetequipment including layer 2, 3, 4 and 7 Ethernet switches and Ethernetnetwork interface cards (NICs) to connect to, communicate with andprovide services for SANs that are based on Fibre Channel technology orhave Fibre Channel interfaces. All of the above can be accomplished byusing an apparatus that transforms Fibre Channel data into Ethernetframes and visa-versa. This apparatus is called a Fibre Channel overEthernet Transformer (FCoE Transformer). Additional SAN switchingfunctions such as device virtualization can be provided by an FCoEFabric. An FCoE Fabric is an Ethernet switch that provides FCoE Fabricservices.

An FCoE Transformer is the interface between the Ethernet and the FibreChannel SAN network. The FCoE Transformer is responsible for convertingthe FCoE protocol to the Fibre Channel FC-1 protocol and vise-versa.Each FCoE Transformer has at least two ports; an Ethernet Port and aFibre Channel port. An FCoE capable NIC or embedded MAC (an FCoE port)in a server can communicate with multiple FCoE Transformers. Thesecommunications are referred to as an association between an FCoE portand a Transformer. The FCoE port in a server is referred to as an FCoEHost Bus Adapter (HBA). When initializing and associating with one ormore FCoE ports, the FCoE Transformer performs link and loopinitialization and participates in physical address assignment under thedirection of an Ethernet port. Once initialized and associated, the FCoETransformer translates FC-1 data frames, primitive signals and primitivesequences to and from FCoE frames. An FCoE Transformer may be usedbetween any Fibre Channel HBA, fabric or device and any FCoE HBA orFabric. Specifically, an FCoE Transformer can be used between an FC HBAand an FCoE Fabric or it may be used between an FCoE Fabric and a FibreChannel device. Two FCoE Transformers may be used back to back on theEthernet interface without an intervening FCoE fabric.

Transporting Fibre Channel data over Ethernet is enabled by a number ofcooperating methods; a method to transport Fibre Channel data framesover Ethernet, a method to transport Fibre Channel primitive sequencesover Ethernet, a method to locate an FCoE Transformer or an FCoE Fabric,a method to associate an FCoE port with an FCoE Transformer or Fabric,and a method to manage an FCoE Transformer, among others.

Once Fibre Channel data is being transported over Ethernet, a number ofnew features and devices are enabled. One preferred embodiment of thisis performing Fibre Channel encryption using Ethernet devices. Anotherpreferred embodiment is performing storage management using Ethernetdevices.

Methods of constructing the FCoE Transformer include using independentEthernet and Fibre Channel interfaces connected by a network processor,by using a Field Programmable Gate Array (FPGA), by using a specialpurpose ASIC, by software running on a Ethernet or Fibre Channelconnected device, by hardware state machines, or by a combination ofhardware and software. The FCoE Transformer can be placed on an EthernetNIC, in an Ethernet MAC, in an Ethernet switch, in a Fibre Channelswitch, in a Fibre Channel HBA, or anyplace in between a Fibre Channeldevice and an Ethernet device. An appreciation of the other aims andobjectives of the present invention and a more complete andcomprehensive understanding of this invention may be obtained bystudying the following description of a preferred embodiment, and byreferring to the accompanying drawings.

A BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of the classical ISO protocol layering stack.

FIG. 2 is an illustration of the Fibre Channel protocol architecture

FIG. 3 is an illustration of the Ethernet protocol architecture

FIG. 4 is an illustration of the FCoE protocol architecture.

FIG. 5 is an illustration which shows a data center with both a LAN anda SAN.

FIG. 6 is an illustration which shows a data center with a merged L2-7Ethernet topology

FIG. 7 is an illustration which shows a data center with a mergedLAN/SAN data center topology

FIG. 8 is an illustration which shows a network topology containing anFCoE HBA, an FCoE Transformer and a Fibre Channel SAN.

FIG. 9 is an illustration which shows a network topology containing anFCoE HBA, an FCoE Fabric, an FCoE Transformer and a Fibre Channel SAN.

FIG. 10 is an illustration which shows the detail of an FCoE Fabric.

FIG. 11 is an illustration which shows a network topology containing aFibre Channel HBA, FCoE Transformers, an FCoE Fabric and a Fibre ChannelSAN.

FIG. 12 is an illustration of the Fibre Channel frame format.

FIG. 13 is an illustration of the Ethernet frame format.

FIG. 14 is an illustration of the FCoE frame format.

FIG. 15 is an illustration of the FCoE header format.

FIG. 16 is an illustration of the FCoE Association header format.

FIG. 17 is an illustration of the FCoE Transport header format.

FIG. 18 is an illustration of the FCoE Primitive header format.

FIG. 19 is an illustration of the FCoE Management header format.

FIG. 20 is an illustration of an Ethernet frame containing a FCoE framecontaining a Fibre Channel frame.

FIG. 21 is an illustration which shows the detail of an FCoETransformer.

FIG. 22 is an illustration which shows a how the FCoE components can beconnected together.

A DETAILED DESCRIPTION OF PREFERRED & ALTERNATIVE EMBODIMENTS I.Overview of the Invention

The present invention provides methods and apparatus for transportingFibre Channel data over Ethernet. Fibre Channel data frames, primitivesignals and primitive sequences are collectively called Fibre Channeldata. The protocol that describes the transformation of Fibre Channeldata into Ethernet frames and visa-versa is called the Fibre Channelover Ethernet (FCoE) protocol. The apparatus that transforms FibreChannel data into Ethernet frames and visa-versa is called a FibreChannel over Ethernet Transformer.

In one preferred embodiment, the task of encrypting a Fibre Channelpayload is performed using an Ethernet device. In another preferredembodiment, the task of performing storage management of a Fibre Channelpayload is performed using an Ethernet device.

In other preferred embodiments, other tasks and sequences of tasks maybe performed on Fibre Channel data using Ethernet based devices. Thetasks and sequences of tasks are described in further detail below.

FIG. 1 generally illustrates the classic ISO protocol layering stack.The Physical layer 1 communicates with the Data Link layer 2. The DataLink layer 2 communicates with the Network layer 3. The Network layer 3communicates with the Transport layer 4. The Transport layer 4communicates with the Session layer 5. The Session layer 5 communicateswith the Presentation layer 6. The Presentation layer 6 communicateswith the Application layer 7. When a given layer is not present, thelower layer communicates with the next higher layer. For example, if theSession layer 5 and the Presentation layer 6 are not present, theTransport layer 4 communicates directly with the Application layer 7.

FIG. 2 generally illustrates the Fibre Channel protocol stack. The FibreChannel Media layer and the Fibre Channel Transmitters and Receiverslayer form the Fibre Channel Physical layer 8. The Fibre ChannelPhysical layer 8 communicates with the Fibre Channel TransmissionProtocol 9. The Fibre Channel Transmission Protocol 9 communicates withthe Fibre Channel Signaling Protocol 10. The Fibre Channel CommonServices and the Fibre Channel Link Services are taken together to formthe Fibre Channel layer 3 protocol 11. The Fibre Channel Signalingprotocol 10 communicates with the Fibre Channel layer 3 protocol 11. TheFibre Channel layer 3 protocol 11 communicates with the Fibre ChannelUpper Layer Protocol Interface Protocol 12. The Fibre Channel UpperLayer Protocol Interface Protocol 12 communicates with the Upper LayerProtocol.

FIG. 3 generally illustrates the Ethernet protocol stack. The EthernetPhysical layer 13 communicates with the Ethernet Media Access Controllayer 14. The Ethernet Media Access Control layer 14 communicates withthe Ethernet Logical Link Control layer 15. The Ethernet Logical LinkControl layer 15 communicates with the Ethernet Upper Layer Protocols18.

FIG. 4 generally illustrates the FCoE protocol stack. The EthernetPhysical layer 13 communicates with the Ethernet Media Access Controllayer 14. The Ethernet Media Access Control layer 14 communicates withthe Ethernet Logical Link Control layer 15. The Ethernet Logical LinkControl layer 15 communicates with the FCoE protocol 17. The FCoEprotocol 17 communicates with the Fibre Channel Signaling protocol 10.The Fibre Channel Signaling protocol 10 communicates with both the FCoEprotocol 17 and the Fibre Channel Transmission protocol 9. The FibreChannel Transmission protocol 9 communicates with the Fibre Channelphysical layer 8.

FIG. 5 is a schematic depiction of the embodiments of a computer networkto which the present invention pertains as Transporting Fibre Channelover Ethernet from the servers 32. Routers 30 are attached to anexternal network (not shown). Routers 30 are also attached to firewalls28 via an ethernet local area network 21. The firewalls 28 are connectedto layer 4-7 switches 26 via an ethernet local area network 21. Thelayer 4-7 switches 26 are connected to the layer 2 switches 24 via anethernet local area network 21. The layer 2 switches 24 are connected tothe servers 32 via an ethernet local area network 21. The servers 32 areconnected to a Fibre Channel switch 22 via a fibre channel storage areanetwork 20. A Fibre channel device 23 is connected to the fibre channelstorage area network 20.

FIG. 6 is a schematic depiction of the embodiments of a computer networkto which the present invention pertains as Transporting Fibre Channelover Ethernet from the servers 32. Routers 30 are attached to anexternal network (not shown). Routers 30 are also attached to firewalls28 via an ethernet local area network 21. The firewalls 28 are connectedto layer 2-7 switches 34 via an ethernet local area network 21. Thelayer 2-7 switches 34 are connected to the servers 32 via an ethernetlocal area network 21. The servers 32 are connected to a Fibre Channelswitch 22 via a fibre channel storage area network 20. A Fibre channeldevice 23 is connected to the fibre channel storage area network 20.

FIG. 7 is a schematic depiction of the embodiments of a computer networkto which the present invention pertains as Transporting Fibre Channelover Ethernet from the servers 32. Routers 30 are attached to anexternal network (not shown). Routers 30 are also attached to firewalls28 via an ethernet local area network 21. The firewalls 28 are connectedto LAN/SAN switches 36 via an ethernet local area network 21. TheLAN/SAN switches 36 are connected to the servers 32 via an ethernetlocal area network 21. The LAN/SAN switches 36 are also connected to thefibre channel storage area network 20. A Fibre channel device 23 isconnected to the fibre channel storage area network 20.

FIG. 8 is a schematic depiction of an embodiment of the invention. Aserver 32 contains a virtual Fibre Channel Host Bus Adapter (HBA) 40.The virtual Fibre Channel HBA 40 contains a number of virtual FibreChannel N-Ports 42 and an Ethernet interface 44. The virtual FibreChannel HBA 40 is connected to an Ethernet layer 2 switch 24 via anethernet local area network 21. The Ethernet layer 2 switch 24 is alsoconnected to an FCoE Transformer 46 via an ethernet local area network21. The FCoE Transformer 46 is connected to the Fibre Channel storagearea network 20. Contained within the FCoE Transformer 46 are a numberof real Fibre Channel N-Ports 48 that correspond to the virtual FibreChannel N-Ports 42.

FIG. 9 is a schematic depiction of an embodiment of the invention. Aserver 32 contains a virtual Fibre Channel Host Bus Adapter (HBA) 40.The virtual Fibre Channel HBA 40 contains a number of virtual FibreChannel N-Ports 42 and an Ethernet interface 44. The virtual FibreChannel HBA 40 is connected to an Ethernet layer 2 switch 24 via anethernet local area network 21. The Ethernet layer 2 switch 24 is alsoconnected to an FCoE Transformer 46 via an ethernet local area network21. The Ethernet layer 2 switch 24 is also connected to an FCoE Fabric50 via an ethernet local area network 21. The FCoE Transformer 46 isconnected to the Fibre Channel storage area network 20. Contained withinthe FCoE Transformer 46 are a number of real Fibre Channel N-Ports 48that correspond to the virtual Fibre Channel N-Ports 42.

FIG. 10 is a schematic description of an embodiment of the inventionshowing the FCoE Fabric detail. The FCoE Fabric 50 contains apparatus toperform Fibre Channel services 56, operating on Well Known Fibre Channelports 54, Virtual Fibre Channel N-Ports 42, Virtual Fibre ChannelF-Ports 58, and ethernet interfaces 44. The FCoE Fabric 50 also containsa FCoE Management function 60 and a Storage Switching Function 52.

FIG. 11 is a schematic depiction of an embodiment of the invention. Aserver 32 contains a Fibre Channel Host Bus Adapter (HBA) 61. The FibreChannel HBA 61 contains a number of Fibre Channel N-Ports 62. The FibreChannel HBA 61 is connected to an FCoE Transformer 46. The FCoETransformer 46 is connected to an Ethernet layer 2 switch 24 via anethernet local area network 21. The Ethernet layer 2 switch 24 is alsoconnected to a second FCoE Transformer 46 via an ethernet local areanetwork 21. The Ethernet layer 2 switch 24 is also connected to an FCoEFabric 50 via an ethernet local area network 21. The second FCoETransformer 46 is connected to the Fibre Channel storage area network20. A Fibre channel device 23 is connected to the fibre channel storagearea network 20.

FIG. 12 generally illustrates the Fibre Channel frame format 71. A validFibre Channel frame 71 starts with a Start Of Frame (SOF) delimiter 70.The SOF delimiter 70 is followed by the Fibre Channel Frame Header 72.The Fibre Channel Frame Header 72 is optionally followed by one or moreoptional headers 74. A Fibre Channel frame 71 may contain a payload 76.A Fibre Channel frame 71 ends with a CRC field 78 and an End Of Frame(EOF) delimiter 80.

FIG. 13 generally illustrates the Ethernet frame format 83. A validEthernet frame 83 starts with a Start Of Frame (SOF) delimiter 82. TheSOF delimiter 82 is followed by the Ethernet Frame Header 84. AnEthernet frame 83 contains a payload 86. An Ethernet frame 83 ends witha CRC field 88 and an End Of Frame (EOF) delimiter 90.

FIG. 14 generally illustrates the Fibre Channel over Ethernet (FCoE)frame format 93. An FCoE frame 93 starts with an FCoE Header 92 and isfollowed by an FCoE Type Header 94. An FCoE frame 93 may contain apayload 96.

FIG. 15 generally illustrates the Fibre Channel over Ethernet (FCoE)Header format 92. An FCoE Header 92 starts with a Version field 98 andis followed by a Type field 100, an Interface Port Identifier field 102and an Interface Identifier field 104.

FIG. 16 generally illustrates the FCoE Association header 107. The FCoEAssociation header 107 is used for the FCoE Type header 94 when the Typefield 100 is specified as Association. An FCoE Association Header 107starts with an Operation field 106 and is followed by a Sequence field108, a Fabric Physical Address field 110, a Last Physical Address field112, a Hard Physical Address field 114, a state field 116, a Port Namefield 118 and a Physical Address Map 120.

FIG. 17 generally illustrates the FCoE Transport header 123. The FCoETransport header 123 is used for the FCoE Type header 94 when the Typefield 100 is specified as Transport. An FCoE Transport Header 123 startswith a Device field 122 and is followed by a Start Of Frame (SOF) field124, an End Of Frame field 126, a flags field 128, a length field 130, afragment offset field 132 and an FCoE ID field 134.

FIG. 18 generally illustrates the FCoE Primitive Header 137. The FCoEPrimitive header 137 is used for the FCoE Type header 94 when the Typefield 100 is specified as Primitive. An FCoE Primitive Header 137 startswith a Id field 134 and is followed by a Primitive field 136, an OrderedSet byte 3 field 138 and an Ordered Set byte 4 field 140.

FIG. 19 generally illustrates the FCoE Management Header 143. The FCoEManagement header 143 is used for the FCoE Type header 94 when the Typefield 100 is specified as Management. An FCoE Management Header 143starts with an Operation field 142 and is followed by a Structure Indexfield 144, a Sequence field 146 and a Variable Index field 148.

FIG. 20 generally illustrates a Fibre Channel frame 71 being transportedin an FCoE frame 93 in an Ethernet frame 83. Within the FCoE frame 93,an FCoE Header 92 and an FCoE Transport header 123 are used.

FIG. 21 is a schematic description of an embodiment of the inventionshowing the FCoE Transformer detail. The FCoE Transformer 46 containsone or more Ethernet interfaces 150, one or more Fibre Channelinterfaces 158, apparatus to perform FCoE Management services 154,apparatus to perform FCoE Transformer services 156 and apparatus toperform FCoE Association services 152.

FIG. 22 is a schematic depiction of an embodiment of the invention. Aserver 32 contains and is connected to a virtual Fibre Channel Host BusAdapter (HBA) 40. The virtual Fibre Channel HBA 40 is connected to anEthernet LAN/SAN switch 36. The Ethernet LAN/SAN switch 36 is alsoconnected to several FCoE Transformers 46. A second server 32 containsand is connected to a Fibre Channel HBA 61. The Fibre Channel HBA 61 isconnected to an FCoE Transformer 46. The FCoE Transformer 46 isconnected to the Ethernet LAN/SAN switch 36. Additional FCoETransformers 46 are connected to the Ethernet LAN/SAN switch 36 and toother Fibre Channel storage area network devices (not shown).

The Fibre Channel protocol has been designed as a layered protocol andgenerally follows the ISO reference protocol model shown in FIG. 1. In alayered protocol architecture, each layer has a specific responsibility.For example, the Data Link layer 2 of the ISO reference protocol modelis responsible for providing and controlling access to the physicalmedia described in the Physical layer 1. The Fibre Channel protocolprovides services at the physical 1, Data Link 2, Network 3 andTransport 4 layers.

The Ethernet protocol has also been designed as a layered protocol andgenerally follows the ISO reference protocol model shown in FIG. 1. TheEthernet protocol provides services at the physical 1 and Data Link 2layers.

Within a protocol architecture, most of the information is containedwithin the data frame and the various protocol headers and trailers.Some of the protocol information is external to the data frames.Examples of external data are the Start Of Frame characters 70, 82, theEnd Of Frame characters 80, 90 and Fibre Channel primitive signals andsequences. When information is external to the data frame and must becommunicated over a non-native medium, such a Fibre Channel overEthernet, a mechanism must exist to carry this external data.

II. Apparatus for Transporting Fibre Channel Over Ethernet

The apparatus for Transporting Fibre Channel over Ethernet is called anFCoE Transformer 46. An FCoE Transformer 46 is the interface between theEthernet and the Fibre Channel networks. The FCoE Transformer 46 isresponsible for converting the FCoE protocol to the Fibre Channel FC-1protocol and vise-versa. Each FCoE Transformer 46 has at least twointerfaces; an Ethernet interface 150 and a Fibre Channel interface 158.When initializing and associating with one or more Fibre Channelinterfaces 158, the FCoE Transformer 46 performs link and loopinitialization and participates in physical address assignment under thedirection of commands received by an Ethernet interface 150. The detailsof the methods of operation of Associating with Fibre Channel overEthernet devices are described below. Once initialized and associated,the FCoE Transformer 46 translates FC-1 data frames and primitivesequences to and from FCoE frames. The novel use of the FCoE protocoland Ethernet as a replacement for the Fibre Channel FC-1 and FC-0protocols allows Ethernet devices to transport Fibre Channel data. Thedetails of the methods of operation of Transporting Fibre Channel dataover Ethernet are described below.

An FCoE Transformer 46 may be used between any Fibre Channel HBA 60,Fibre Channel Switch 22, Fibre Channel storage area network 20, or otherFibre Channel interface and any FCoE HBA 40 or FCoE Fabric 50.Specifically, an FCoE Transformer 46 can be used between an FC HBA 61and an FCoE Fabric 50 or it may be used between an FCoE Fabric 50 and aFibre Channel storage area network 20 or fibre channel device 23. Thedetails of the methods of operation of Managing Fibre Channel overEthernet devices are described below.

III. Methods of Operation of Transporting Fibre Channel Over Ethernet

To transport Fibre Channel data over Ethernet, one must be able todifferentiate between the various types of Fibre Channel data and have amethod to appropriately process each type of data. Fibre Channel hasthree types of data, Fibre Channel frames 71, Fibre Channel Primitivesignals and Fibre Channel Primitive Sequences. The details of themethods of operation of Transporting Fibre Channel Data Frames overEthernet and the Transporting Fibre Channel Primitive Signals overEthernet are described below. In one preferred embodiment, Fibre Channelprimitive sequences are consumed by the FCoE Transformer 46 and theresults are generally communicated through the FCoE Association method.The details of the methods of operation of Associating with FibreChannel over Ethernet devices are described below. In another preferredembodiment, the primitive sequences are transported over Ethernet usingthe same mechanism as primitive signals.

To unambiguously describe the type of the Fibre Channel data carriedwithin an FCoE frame 93, and the FCoE Transformer 46 and Fibre Channelinterface 158 on a given FCoE Transformer 46 to whom it is destined,this information must be specified in all communications to and from aFCoE Transformer 46. This information is specified in the FCoE Header92. The FCoE Header 90 is composed of a Version field 98, a Type field100, an Interface Port Identifier field 102 and an Interface Identifierfield 104. The Version field 98 is used to insure that the format of theFCoE Header 46 has not changed. The Type field 100 is used to determinethe format and length of the FCoE Type Header 94 that immediatelyfollows the FCoE Header 46. The Interface Port Identifier field 102identifies which Fibre Channel interface 158 an FCoE frame 93 isreferencing. The Interface Port Identifier field 102 is generallyexpected to be a ones based index of the Fibre Channel interfaces 158.The Interface Port Identifier field 102 can be eliminated in analternative embodiment that supports only one Fibre Channel interface158 per FCoE Transformer 46. The Interface Identifier field 104unambiguously identifies an FCoE transformer 46 when it has more thanEthernet interfaces 150. The Interface Identifier field 104 is generallyexpected to contain the Ethernet Address of the first Ethernet interface150. The Interface Identifier field 104 can be eliminated in analternate embodiment that supports only one Ethernet interface 150 perTransformer 46.

IV. Methods of Operation of Transporting Fibre Channel Data Frames OverEthernet

When the FCoE Type 100 of the FCoE Header 92 is specified as Transport,the FCoE Header 92 is immediately followed by the FCoE Transport header123. The FCoE Transport header 123 is composed of a series of fields122, 124, 126, 128, 130, 132, 134 which allow a Fibre Channel frame tobe carried and delivered unambiguously to its destination using one ormore Ethernet frames 83 for transport. The device address field 122contains the physical Fibre Channel address of the Fibre Channel deviceto which is being addressed through the FCoE Transformer 46.

Both gigabit Ethernet and Fibre Channel protocols use the same encodingmechanism, 8 B/10 B. While the same encoding mechanism is used, themethod in which specific codes are used differs considerably. An exampleof this is how an SOF 70 and EOF 80 of a Fibre Channel frame are usedand how an SOF 82 and EOF 90 of an Ethernet frame are used. In Ethernet,the SOF 82 character simply indicates the Start Of frame, while in FibreChannel; the SOF 70 character indicates both the Start Of Frame and theframe class. Specifically, the SOF character 70 and the EOF character 80vary depending upon the data contained within the Fibre Channel frame71. The SOF character 70 is encoded into the SOF field 124 of the FCoETransport header 123 of the FCoE frame 93. The EOF character 80 isencoded into the EOF field 126 of the FCoE Transport header 123 of theFCoE frame 93.

The flags field 128 contains implementation specific indicators. Theseindicators indicate when additional fragments follow and when the FibreChannel CRC 78 is valid. The length field 130 contains the length of theFibre Channel frame that forms the payload. The fragment offset field132 indicates where in the receiving FCoE Transformer's 46 buffer thepayload should be placed. The fragment offset field 132 is measured inunits of 64 bytes (512 bits). When the fragment offset field 132 is setto zero, the payload should start at the beginning of the buffer. Anon-fragmented FCoE Transport frame must have the fragment offset field132 set to zero and must have the last fragment indicator in the flagsfield 128 set. This FCoE frame must be sent in a single Ethernet frame.The FCoE ID 134 contains a unique identification for each Fibre Channelframe. The FCoE ID 134 must be the same for all fragments of a singleFibre Channel frame. The FCoE ID 134 should be different for each newreceived Fibre Channel frame.

When a Fibre Channel frame 71 is received by an FCoE Transformer 46, itis specifically received by one of the Fibre Channel interfaces 158. Thereceiving Fibre Channel interface 158 sends the Fibre Channel frame 71to the FCoE Transformer Services function 156.

The Fibre Channel Transformer Services function 156 creates an FCoEheader 92 with the type field 100 set to Transport. The Fibre ChannelTransformer Services function 156 sets the Version field 98, theInterface Port Identifier field 102 and the Interface Identifier field104 to the correct values for the FCoE Transformer 46. The Fibre ChannelTransformer Services function 156 then creates an FCoE type header 94 oftype FCoE Transport header 123. The Fibre Channel Transformer Servicesfunction 156 sets the device field 122 to the Fibre Channel physicaladdress of the Fibre Channel device from which the Fibre Channel frame71 was received. The SOF field 124 is set to a unique value thatcorresponds to the SOF field 70 of the Fibre Channel frame 71. The EOFfield 126 is set to a unique value that corresponds to the value of theEOF field 80 of the Fibre Channel frame 71. The values used in the SOFfield 124 and the EOF field 126 may be equal to the 8-bit representationof the Fibre Channel SOF and EOF characters or any other value thatallows an FCoE device to recognize the various SOF and EOF charactersused by Fibre Channel.

If the complete Fibre Channel frame 71 will fit in the payload 96 of theFCoE frame 93, then the flags field 128 has the last offset bit set andthe fragment offset field 132 is set to zero. The length field 130 isset to the length of the Fibre Channel frame 71. If the Fibre ChannelCRC field 78 is valid, then the CRC valid bit in the flags field 128 isset. The FCoE ID field 134 is set to a unique value.

If the complete Fibre Channel frame 71 will not fit in the payload 96 ofthe FCoE frame 93, then the Fibre Channel frame 71 must be fragmentedacross several FCoE frames 93. For each frame other that the last frame,the flags field 128 must not have the last fragment bit or the CRC validbit set. For the last frame, the flags field 128 must have the lastfragment bit set and if the Fibre Channel CRC field 78 is valid, thenthe CRC valid bit in the flags field 128 must be set. For all FCoEframes 93 containing fragments of a single Fibre Channel frame 71, thefragment offset field 132 is set to the offset where the fragmentbegins. The length field 130 is set to the length of the data in theFCoE payload 96. The FCoE ID field 134 is set to a unique value that isthe same for all Fibre Channel fragments.

Once the FCoE frame 93 or FCoE frames 93 have been constructed, they aresent to the Ethernet interface 150 for transmission. There is a one toone correspondence between the received Fibre Channel frames 71 and thetransmitted FCoE frames 93 when the Fibre Channel frames 71 are notfragmented.

When an FCoE frame 93 is received by the Ethernet interface 150, theprocess is reversed. The Ethernet interface 150 sends the received FCoEframe 93 the FCoE Transformer Services function 156. The FCoETransformer Services function 156 examines the FCoE type field 100. Ifthe type field 100 is not set to Transport, the FCoE TransformerServices 156 processes the received FCoE frame 93 as described elsewherein this document. If the type field is set to Transport, the FCoEpayload 96 is extracted as the Fibre Channel frame 71. The Fibre ChannelSOF 70 is set to the value in the SOF field 124. The Fibre Channel EOF80 is set to the value in the EOF field 126. If the CRC valid bit notset in the flags field 128, then the Fibre Channel CRC is calculated andthe CRC field 78 is set to the calculated value. If the last fragmentbit is set in the flags field 128 and the fragment offset field 132 isset to zero, the entire Fibre Channel frame 71 is contained within asingle FCoE frame 93. If either of the last fragment bit in the flagsfield 128 is not set or the fragment offset field 132 is non-zero, thenthe Fibre Channel frame 71 must be reassembled from the various FCoEfragments. A complete Fibre Channel frame 71 has been received when eachthe accumulated lengths of the fragments without the last fragment bitin the flags field 128 set equals the fragment offset field 132 of theFCoE fragment with the last fragment bit set in the flags field 128. Allof the fragments must have the same value in the FCoE ID field 134 andmust have a different value in the fragment offset field 132. Thecompleted Fibre Channel frame 71 is then sent to the Fibre Channelinterface 158 to be sent to the Fibre Channel device specified in thedevice field 122.

V. Methods of Operation of Transporting Fibre Channel Primitive SignalsOver Ethernet

When the FCoE Type 100 of the FCoE Header 92 is specified as Primitive,the FCoE Header 92 is immediately followed by the FCoE Primitive header137. The FCoE Primitive header 137 is composed of a series of fields122, 136, 138, 140 which allow a Fibre Channel primitive to be carriedand delivered unambiguously to its destination using an Ethernet frame83 for transport. The device address field 122 contains the physicalFibre Channel address of the Fibre Channel device that is beingaddressed through the FCoE Transformer 46. The primitive field 136specifies the specific ordered set being carried by the FCoE Primitiveheader 137. Some ordered sets require one or two additional ordered setsto be specified. These additional ordered sets are specified in the OSbyte 3 field 138 and the OS byte 4 field 140.

When a Fibre Channel primitive signal is received by an FCoE Transformer46, it is specifically received by one of the Fibre Channel interfaces158. The receiving Fibre Channel interface 158 sends the Fibre Channelprimitive sequence to the FCoE Transformer Services function 156.

The Fibre Channel Transformer Services function 156 creates an FCoEheader 92 with the type field 100 set to Primitive. The Fibre ChannelTransformer Services function 156 sets the Version field 98, theInterface Port Identifier field 102 and the Interface Identifier field104 to the correct values for the FCoE Transformer 46. The Fibre ChannelTransformer Services function 156 then creates an FCoE type header 94 oftype FCoE Primitive header 137. The Fibre Channel Transformer Servicesfunction 156 sets the device field 122 to the Fibre Channel physicaladdress of the Fibre Channel device from which the Fibre Channelprimitive sequence was received. The Primitive field 136 is set to thevalue of the primitive received. If the received primitive has orderedset specific values for bytes 3 and 4, these values are placed in the OSbyte 3 138 and OS byte 4 140 fields respectively.

Once the FCoE frame has been constructed, it is sent to the Ethernetinterface 150 for transmission. There is a one to one correspondencebetween the received Fibre Channel primitive signals and the transmittedFCoE frames 93. FCoE PR frames are never large enough to requirefragmentation.

When an FCoE frame 93 is received by the Ethernet interface 150, theprocess is reversed. The Ethernet interface 150 sends the received FCoEframe 93 the FCoE Transformer Services function 156. The FCoETransformer Services function 156 examines the FCoE type field 100. Ifthe type field 100 is not set to Primitive, the FCoE TransformerServices 156 processes the received FCoE frame 93 as described elsewherein this document. If the type field is set to Primitive, the primitivefield 136 is extracted from the FCoE frame 93. A Fibre Channel primitivesignal is created according to the value extracted from the primitivefield 136. If the extracted primitive has ordered set specific valuesfor bytes 3 and 4, these values are extracted from the OS byte 3 138 andOS byte 4 140 fields respectively. The completed Fibre Channel primitivesignal is then sent to the Fibre Channel interface 158 to be sent to theFibre Channel device specified in the device field 122.

VI. Methods of Operation of Associating with Fibre Channel Over EthernetDevices

The FCoE protocol provides a mechanism for an FCoE Transformer 46 todynamically associate with one or more Ethernet interfaces 150 on eitherFCoE HBAs 40 or FCoE Fabrics 50. This enables FCoE HBAs 40 or FCoEFabrics 50 to have a Fibre Channel Physical Addresses (FC-PA) assignedto it. The novel ability of an Ethernet interface 44 to have a FibreChannel physical address assigned to it enable the Ethernet devices 40,50 to communicate with Fibre Channel devices without being directlyconnected to the Fibre Channel network. The FCoE Transformer 46 maps theFibre Channel physical addresses to Ethernet MAC addresses. The FCoETransformer 46 only performs this mapping when it has been instructed toestablish link with the Fibre Channel fabric, loop or device. An FCoETransformer 46 may be associated with more than one Ethernet interface44. The FCoE Association method includes a method to dynamicallydiscover FCoE Transformers 46 and Interfaces, and a method todynamically associate and disassociate with an FCoE Transformer 46 or adevice performing FCoE Transformer 46 functionality.

When the FCoE Type 100 of the FCoE Header 92 is specified asAssociation, the FCoE Header 92 is immediately followed by the FCoEAssociation header 107. The FCoE Association header 107 is composed of aseries of fields 106, 108, 110, 112, 114, 116, 118, 120 which allow anFCoE Interface to discover and associate with an FCoE Transformer 46.The Operation field 106 can be set to one of the following values;Interface Announce, Interface Query, Link Control, Link State, LinkQuery. The Sequence field 108 indicates that the value of the statefield 116 has changed. All FCoE Transformers 46 must increment thisfield any time the state field 116 in a transmitted FCoE Associationheader 107 is different from the last transmitted value. The PhysicalAddress Fabric field 110 is only valid in a Link Control operation. ThePhysical Address Fabric field 110 is set to the last Fibre Channelphysical address assigned by the Fibre Channel fabric during the FibreChannel fabric login process. If no address has been assigned by theFibre Channel fabric, the Physical Address Fabric field 110 should beset to unassigned. The Physical Address Last field 112 is only valid ina Link Control or a Link State operation. In a Link Control operation,the Physical Address Last field 112 is set to the last physical addressthat was assigned to the Ethernet interface 44. In a Link Stateoperation, the Physical Address Last field 112 is set to the physicaladdress that has just been assigned to the Ethernet interface 44 by theFCoE Transformer. If no address has been previously assigned by the FCoETransformer 46, the Physical Address Last field 112 should be set tounassigned. The Physical Address Hard field 114 is only valid in a LinkControl operation. The Physical Address Fabric Hard 114 is set to thespecific Fibre Channel physical address requested by the Ethernetinterface hardware, such as a switch on the front panel of the device.If no specific address has been requested by the Ethernet interface, thePhysical Address Hard field 114 should be set to unassigned. The Statefield 116 contains a description of the Fibre Channel and Ethernetcapabilities of the FCoE Transformer 46 as requested by the Ethernetinterface 44 or as provided by the FCoE Transformer 46. The Port Namefield 118 contains the Fibre Channel world wide name associated with theEthernet interface 44. The Map field 120 contains a map of all FibreChannel devices attached to the FCoE Transformer 46 on the Fibre Channelport described by the interface port identifier field 102. The format ofthe Map field is defined in the Fibre Channel Arbitrated Loopspecification.

When an FCoE Transformer 46 is initialized, it establishes link on itsEthernet interfaces 150. It does not establish link with its FibreChannel interfaces 158 at this time. After the Ethernet link isestablished, the FCoE Association Services function 152 periodicallybroadcasts an FCoE Association message 107 with the operation field 106set to Interface Announce. An FCoE Transformer 46 broadcasts thesemessages until the FCoE Association Services function 152 receives anFCoE Association message with the type field set to Link Control. TheseFCoE Interface Announce messages are broadcast at intervals of 0.1seconds to 1 second.

When an FCoE HBA 40 is initialized, it establishes link with itsEthernet interface 44. After the Ethernet link is established, the FCoEAssociation Services function 152 broadcasts an FCoE Association message107 with the operation field 106 set to Interface Query to determinewhat FCoE Fabrics and FCoE Transformers are connected to the Ethernet.

When an FCoE Transformer 46 receives an FCoE Interface Query message, itresponds with a unicast FCoE Interface Announce message. When an FCoEHBA 40 receives an FCoE Interface Announce message from an FCoETransformer 46 it saves the Ethernet address of the FCoE Transformer 46in an interface table. With the Ethernet address, the FCoE HBA 40 cannow instruct the FCoE Transformer 46 to establish the Fibre Channel linkand obtain a Fibre Channel Physical Address

An FCoE HBA 40 can discover an FCoE Transformer 46 based on either anInterface Announce broadcast or an Interface Announce unicast responseto an Interface Query message. An FCoE Transformer 46 can discover anFCoE HBA 40 based on either an Interface Query message broadcast or aLink Config message.

Once an FCoE Transformer 46 has been discovered by an FCoE HBA 40, theFCoE HBA 40 may request that the FCoE Transformer 46 initialize itsFibre Channel interface 158 and have a Fibre Channel Physical Addressassigned. The FCoE HBA 40 sends an FCoE Association Link Control messageto the FCoE Transformer 46. This message contains the Fibre Channel PortName 118, the desired physical address 114, the last physical address112, the last fabric assigned physical address 110 and the desired linkcharacteristics 116. Upon receiving an FCoE Association Link Controlmessage, the FCoE Transformer 46 attempts to establish the Fibre Channellink in accordance with the parameters specified in the message. Uponsuccess or failure, the FCoE Transformer 46 responds with an FCoEAssociation Link State message. On success, the FCoE Transformer 46 addsthe assigned Fibre Channel Physical Address and the FCoE HBA's 40Ethernet address into a table so that subsequent traffic can betransformed between the Fibre Channel and the Ethernet networks.

If the link on the Fibre Channel interface 158 fails, for any reason,the FCoE Transformer 46 sends an FCoE Association Link State message toeach of the associated FCoE HBAs 40 indicating that the Fibre Channellink is down. The FCoE Transformer 46 (re)establishes Fibre Channel linkwhen it receives a subsequence FCoE Association Link Control messagefrom the FCoE HBA 40.

An FCoE HBA 40 can change the link state at any time by sending an FCoEAssociation Link Control message to the FCoE Transformer 46. Each LinkControl message is responded to by an FCoE Association Link Statemessage.

An FCoE HBA 40 can query the link state by sending an FCoE AssociationLink Query message. The response to a Link Query message is a Link Statemessage.

Both the FCoE HBA 40 and the FCoE Transformer 46 maintain tables ofFibre Channel Physical Addresses and Fibre Channel Port Names toEthernet address mapping. When either the FCoE HBA 40 or the FCoETransformer 46 loses link on the Ethernet interface 44, 150, theassociated mapping table entries must be flushed.

VII. Methods of Operation of Managing Fibre Channel Over EthernetDevices

The FCoE protocol is designed as an alternative to the Fibre ChannelFC-1 protocol. It is an Ethernet based layer 2 protocol. Because FCoE isused in an Ethernet environment, it is expected that hosts with FCoEHBAs 40 and FCoE Fabrics 50 will use SNMP or a similar, widely deployednetwork management protocol. However, given the desire to build small,simple FCoE Transformers 46 that do not have the ability to run a TCP/IPprotocol stack necessary to implement SNMP, there is a requirement for acompanion to the existing FCoE protocols to implement a simplemanagement function. FCoE Management is meant to be implemented in thespirit of both the FCoE protocol and the SNMP protocol. Alternativeembodiments may use other management protocols or completely eliminatethe management function.

When the FCoE Type 100 of the FCoE Header 92 is specified as Management,the FCoE Header 92 is immediately followed by the FCoE Management header143. The FCoE Management header 143 is composed of a series of fields142, 144, 146, 148 which allow an FCoE management command or response tobe carried and delivered unambiguously to its destination using anEthernet frame 83 for transport. The Operation field 142 can be set toone of the following values; Get Variable, Set Variable, Valid Response,Invalid Response. The Structure Index field 144 describes which group ofvariables the request should operate on. The Structure Index field 144can be set to one of the following values; ConnUnitPortEntry,ConnUnitPortStatEntry. The Sequence field 146 is used to match FCoEmanagement requests with responses. The Sequence field 146 of amanagement response must have the same value as the management request.The Variable Index field 148 specifies the management variable beingoperated on. The FCoE payload field 96 contains the value of thevariable specified by the variable index field 148.

When an FCoE frame 93 is received by the Ethernet interface 150, theEthernet interface 150 sends the received FCoE frame 93 to the FCoETransformer Services function 156. The FCoE Transformer Servicesfunction 156 examines the FCoE type field 100. If the type field 100 isnot set to Management, the FCoE Transformer Services 156 processes thereceived FCoE frame 93 as described elsewhere in this document. If thetype field is set to Management, the FCoE Management frame is sent tothe FCoE Management Services function 154. The FCoE Management Servicesfunction 154 extracts the operation from the operation field 142. If theextracted operation is not Get Variable or Set Variable, an FCoEManagement response with the operation field set to Invalid Response isreturned to the FCoE Management requestor. If the extracted operation isGet Variable or Set Variable, the management variable is extracted fromthe Structure Index field 144 and the Variable Index field 148. If themanagement variable is valid, the given operation is performed. If theoperation is Set Variable, the given variable is set to the valuecontained in the payload field 96. An FCoE Management response frame iscreated from the original FCoE frame 93. The same FCoE Header 92 may beused. The same FCoE Management Header 143 may be used. The operationfield 142 is set to Valid Response. The Structure Index 144 and VariableIndex 148 are set to the Structure Index 144 and Variable Index 148values from the FCoE Management request. The sequence field 146 is setto the sequence field 146 value from the FCoE Management request. If theoperation field 142 of the Management request was set to Get Variable,the value of the requested variable is placed in the payload field 96.Once the FCoE Management response has been completed, it is sent to theEthernet interface 150 for transmission back to the requestor.

VIII. Alternative Embodiments of Transporting Fibre Channel OverEthernet

A preferred embodiment is a Fibre Channel interface with a remote FibreChannel interface.

Another preferred embodiment is an FCiP interface with a remote FibreChannel interface.

Another preferred embodiment is an iFCP interface with a remote FibreChannel interface.

Another preferred embodiment is a Fibre Channel firewall using Ethernetdevices.

Another preferred embodiment is performing Fibre Channel storage datavirtualization using Ethernet devices.

Another preferred embodiment is performing Fibre Channel datareplication using Ethernet devices.

Another preferred embodiment is unifying Fibre Channel and Ethernet onthe backplane of a computer or cluster of computers.

Another preferred embodiment is a Fibre Channel Host Bus Adapter (HBA)using an Ethernet NIC.

Another preferred embodiment is host access of Fibre Channel based datausing Ethernet devices.

Another preferred embodiment is transporting SCSI traffic over FibreChannel over Ethernet.

Another preferred embodiment is performing Fibre Channel data erasureusing Ethernet devices.

Another preferred embodiment is transporting encrypted SCSI traffic overFibre Channel over Ethernet.

Conclusion

Although the present invention has been described in detail withreference to one or more preferred embodiments, persons possessingordinary skill in the art to which this invention pertains willappreciate that various modifications and enhancements may be madewithout departing from the spirit and scope of the Claims that follow.The various alternatives for providing a efficient means fortransporting Fibre Channel over Ethernet that have been disclosed aboveare intended to educate the reader about preferred embodiments of theinvention, and are not intended to constrain the limits of the inventionor the scope of Claims. The List of Reference Characters which followsis intended to provide the reader with a convenient means of identifyingelements of the invention in the Specification and Drawings. This listis not intended to delineate or narrow the scope of the Claims.

LIST OF REFERENCE CHARACTERS  1 Layer 1 Protocol; Physical Layer  2Layer 2 Protocol; Data Link Layer  3 Layer 3 Protocol; Network Layer  4Layer 4 Protocol; Transport Layer  5 Layer 5 Protocol; Session Layer  6Layer 6 Protocol; Presentation Layer  7 Layer 7 Protocol; ApplicationLayer  8 Fibre Channel Physical Layer  9 Fibre Channel TransmissionProtocol  10 Fibre Channel Signaling Protocol  11 Fibre Channel Layer 3Protocol  12 Fibre Channel Upper Layer Protocol Interface Protocol  13Ethernet Physical Layer  14 Ethernet Media Access Control Layer  15Ethernet Logical Link Control  16 Fibre Channel Upper Layer Protocol  17FCoE Protocol  18 Ethernet Upper Layer Protocol  20 Fibre ChannelStorage Area Network  21 Ethernet Local Area Network  22 Fibre ChannelSwitch  23 Fibre Channel Device  24 Layer 2 Ethernet Switch  26 Layer4-7 Ethernet Switch  28 Firewall  30 Router  32 Server  34 Layer 2-7Ethernet Switch  36 LAN/SAN Switch  40 FCoE HBA  42 Virtual FibreChannel Port  44 Ethernet interface  46 FCoE Transformer  48 FibreChannel Interface  50 FCoE Fabric  52 Storage Switching Function  54Well Known Fibre Channel Ports  56 Fibre Channel Services  58 VirtualFibre Channel F-Port  60 FCoE Management Functions  61 FC HBA  62 RealFibre Channel N-Port within an FC HBA  70 SOF field, Fibre Channel Frame 71 Fibre Channel Frame  72 Frame Header, Fibre Channel Frame  74Optional Header, Fibre Channel Frame  76 Payload field, Fibre ChannelFrame  78 CRC field, Fibre Channel Frame  80 EOF field, Fibre ChannelFrame  82 SOF field, Ethernet Frame  83 Ethernet Frame  84 Frame Header,Ethernet Frame  86 Payload field, Ethernet Frame  88 CRC field, EthernetFrame  90 EOF field, Ethernet Frame  92 FCoE Header, FCoE Frame  93 FCoEFrame  94 FCoE Type Header, FCoE Frame  96 Payload field, FCoE Frame  98Version field, FCoE Header 100 Type field, FCoE Header 102 InterfacePort Identifier field, FCoE Header 104 Interface Identifier field, FCoEHeader 106 Operation field, FCoE Association Header 107 FCoE AssociationHeader 108 Sequence field, FCoE Association Header 110 Physical AddressFabric field, FCoE Association Header 112 Physical Address Last field,FCoE Association Header 114 Physical Address Hard field, FCoEAssociation Header 116 State field, FCoE Association Header 118 PortName field, FCoE Association Header 120 Map field, FCoE AssociationHeader 122 Device field, FCoE Transport Header 123 FCoE Transport Header124 SOF field, FCoE Transport Header 126 EOF field, FCoE TransportHeader 128 Flags field, FCoE Transport Header 130 Length field, FCoETransport Header 132 Fragment Offset field, FCoE Transport Header 134FCoE ID field, FCoE Transport Header 136 Primitive field, FCoE PrimitiveHeader 137 FCoE Primitive Header 138 Ordered Set Byte 3 field, FCoEPrimitive Header 140 Ordered Set Byte 4 field, FCoE Primitive Header 142Operation field, FCoE Management Header 143 FCoE Management Header 144Structure Index field, FCoE Management Header 146 Sequence field, FCoEManagement Header 148 Variable Index field, FCoE Management Header 150Ethernet interface, FCoE Transformer 152 FCoE Association Services, FCoETransformer 154 FCoE Management Services, FCoE Transformer 156 FCoETransformer Services, FCoE Transfoimer 158 Fibre Channel interface, FCoETransfomier

1.-20. (canceled)
 21. A method of operating a FCoE Transformer (46)including an Ethernet Interface (44) and a Fibre Channel Interface (48),wherein the method comprises the steps of: receiving, at the FCoETransformer (46), an FCoE Frame (93) via a Layer 2 Ethernet Switch (24);converting, at the FCoE Transformer (46), the FCoE Frame to a FibreChannel Frame (71), wherein: the FCoE Frame (93) includes a SOF field(124) included in an FCoE Transport Header (123) for providing an SOFcharacter used to start the fibre channel frame (71), and the SOF field(124) in the FCoE Transport Header (123) is for encoding the SOF field,Fibre Channel Frame (70), and the FCoE Frame (93) includes an EOF field(126) included in an FCoE Transport Header (123) for providing an EOFcharacter used to end the fibre channel frame (71), and the EOF field(126) in the FCoE Transport Header (123) is for encoding the EOF field,Fibre Channel Frame (80); and transporting the Fibre Channel Frame (71).22. The method of claim 21, further comprising providing a fibre channeldevice (23).
 23. The method of claim 21, further comprising transportingthe Fibre Channel Frame (71) to the fibre channel device (23).
 24. Themethod of claim 21, wherein the FCoE Frame (93) is received from an FCoEHBA (40) that includes a Virtual fibre channel Port (42) and an EthernetInterface (44).
 25. The method of claim 24, wherein the FCoE HBA (40) isconnected to the Layer 2 Ethernet Switch (24).
 26. The method of claim21, further comprising transporting the Fibre Channel Frame (71) to aFCoE Fabric (50).
 27. The method of claim 21, further comprising placingthe FCoE Transformer (46) between a fibre channel device (23) and anEthernet device.
 28. A FCoE Transformer (46) comprising an EthernetInterface (44) and a Fibre Channel Interface (48), wherein the FCoEtransformer (46) is configured to: receive an FCoE Frame (93) via aLayer 2 Ethernet Switch (24); convert the FCoE Frame (93) to a FibreChannel Frame (71), wherein: the FCoE Frame (93) includes a SOF field(124) included in an FCoE Transport Header (123) for providing an SOFcharacter used to start the Fibre Channel Frame (71), and the SOF field(124) in the FCoE Transport Header (123) is for encoding the SOF field,Fibre Channel Frame (70), and the FCoE Frame (93) includes an EOF field(126) included in an FCoE Transport Header (123) for providing an EOFcharacter used to end the Fibre Channel Frame (71), and the EOF field(126) in the FCoE Transport Header (123) is for encoding the EOF field,Fibre Channel Frame (80); and transport the Fibre Channel Frame (71).29. The FCoE Transformer (46) of claim 28, wherein the FCoE is furtherconfigured to transport the Fibre Channel Frame (71) to the fibrechannel device (23).
 30. The FCoE Transformer (46)of claim 28, whereinthe FCoE Frame (93) is received from an FC HBA (40) that includes aVirtual fibre channel Port (42) and an Ethernet Interface (44).
 31. TheFCoE Transformer (46)of claim 28, wherein the FC HBA (40) is connectedto the Layer 2 Ethernet Switch (24).
 32. The FCoE Transformer (46)ofclaim 31, wherein the FCoE is further configured to transport the FibreChannel Frame (71) to a FCoE Fabric (50).
 33. A system comprising: aFCoE Transformer (46) comprising an Ethernet Interface (44) and a FibreChannel Interface (48), wherein the FCoE Transformer (46) is configuredto: receive an FCoE Frame (93) via a Layer 2 Ethernet Switch (24);convert the FCoE Frame (93) to a Fibre Channel Frame (71), wherein: theFCoE Frame (93) includes a SOF field (124) included in an FCoE TransportHeader (123) for providing an SOF character used to start the FibreChannel Frame (71), and the SOF field (124) in the FCoE Transport Header(123) is for encoding the SOF field, Fibre Channel Frame (70), and theFCoE Frame (93) includes an EOF field (126) included in an FCoETransport Header (123) for providing an EOF character used to end theFibre Channel Frame (71), and the EOF field (126) in the FCoE TransportHeader (123) is for encoding the EOF field, Fibre Channel Frame (80);and transport the Fibre Channel Frame (71).
 34. The system of claim 33,wherein the FCoE is further configured to transport the Fibre ChannelFrame (71) to the fibre channel device (23).
 35. The system of claim 33,wherein the FCoE Frame (93) is received from an FC HBA (40) thatincludes a Virtual fibre channel Port (42) and an Ethernet Interface(44).
 36. The system of claim 35, wherein the FC HBA (40) is connectedto the Layer 2 Ethernet Switch (24).
 37. The system of claim 33, whereinthe FCoE is further configured to transport the Fibre Channel Frame (71)to a FCoE Fabric (50).